Flywheel Balance Problems. Please help!!!

Hi, I am new to the forums and would just like to say Hi to all and also ask my first question. I recently installed A billet flywheel and when I started the motor it shook really bad. It was a 50 oz. imbalance flywheel and it was brand new so I didnt even think about balancing it. I called A few machine shops and all they are telling me is that I have to balance the entire engine with the new flywheel. How can that be???? I know they sell these things like mad and I cant imagine that everyone that buys one is having their engine balanced. Has anyone ran into this problem? Do any aftermarket flywheel manufacturers make a TRUE "BOLT IN" flywheel. Any help in this situation would be greatly appreciated. Thanx!!!

Clutch Alignment???

The flywheel was deffinitley a 50oz. imb. It is made by CAT. One of the crank bolts is offset so the flywheel can only be installed one way. The clutch is a ford motorsport, king cobra and it was brand new too. it has a green dot on it...I imagine that is to line it up but what does it line up with???? I have pulled the flywheel out and installed A reman stock unit and the vibration is gone at idle, but is there from 3000-3500RPM. It's not nearly as bad as the billet flywheel, but not near what it was like stock. I did use the clutch centering pins. Maybe the clutch alignment theory is somthing I need to look into. ANY INFO????? Oh yeah the engine ran smooth as glass before any of this....